The present invention generally relates to presses capable of bending plate material or the like. In particular, the present invention is directed to a rugged and dependable adjustable die assembly including a pair of die members capable of being easily, quickly, and accurately positioned relative to one another to allow for selective bending of a workpiece at a variety of predetermined angles and/or radii.
Large capacity hydraulic or mechanical presses, e.g., of about 500 tons and larger capacity, have suffered from long-standing problems preventing quick and accurate adjustment of the die members relative to one another. Because components of the forces generated in such large capacity machine assemblies during the bending of relatively thick steel plate must pass directly through the die members, it has long been considered necessary to employ die members having considerable mass. However, the very mass necessary for withstanding such forces makes it exceedingly difficult to move the die members relative to one another when adjusting the gap between the die members for changing the angle of bend to be formed in the workpiece. Moreover, certain of the temporary fastening or positioning means for the dies which are sufficiently rugged to withstand the aforementioned forces suffer from limitations in respect to versatility and ease of adjustment, while other more versatile and readily adjustable fastening or positioning means suffer from disadvantages of complexity, costliness and inadequate ruggedness.
A known arrangement providing considerable ruggedness and accurate die positioning involves bolting the dies to the inner surfaces of upright sides of an open-top (often open-ended) rigid box or cage. To adjust the die spacing, the dies are unbolted, shims of predetermined thickness are inserted between their back sides and the sides of the box or cage and the dies and sides are then bolted into the box. However, a relatively large number of pairs of shims of various sizes must be employed to provide a wide variety of required bending angles. Because each pair of shims is relatively expensive and must be stored when not in use, this arrangement suffers from disadvantages of cost and storage requirements. More importantly, shims employed in heavy duty press brake assemblies can themselves be exceedingly heavy and cumbersome, often requiring two or more employees just for lifting and positioning the shims. It becomes evident that while shims may vary the gap between die members, shims do not provide a quick, inexpensive, and simple way of adjusting the die members.
In attempts to eliminate the above disadvantages, some presses have been fitted with elaborate carriage mechanisms for moving the die members. However, because such carriage mechanisms are often complex in nature, they are costly and subject to mechanical breakdowns. That they have not fully met existing needs is evidenced by the continuing widespread use of the cumbersome box and shim arrangements described above.
As will become apparent from a reading of the following description and claims, the present invention provides a uniquely constructed adjustable die assembly which overcomes known problems confronting prior art assemblies as discussed hereabove. In particular, the present invention provides a pair of die members capable of being quickly and accurately adjusted relative to the press ram and to one another without the need for any cumbersome shims or costly carriage mechanisms or the like, while resisting force components generated in presses having capacities of up to 500 tons and higher.